1. Technical Field
The present invention relates in general to a method and system for providing communication between a bus and a peripheral device and in particular to a method and system for providing asynchronous communication between a system bus and a peripheral device, wherein the peripheral device is externally connected by a cable to the system bus. Still more particularly, the present invention relates to a method and system for providing bus master and slave capabilities between a system bus and an externally located peripheral device.
2. Description of the Related Art
Generally in computer systems and especially in personal computer systems and in work stations, data is transferred between various elements such as a central processing unit, input/output adapters, input/output devices, bus controllers (i.e., elements that can control the computer system such as bus masters or direct memory access ("DMA") controllers and slaves), bus slaves (i.e., elements that are controlled by bus controllers) as well as memory devices, such as system memory. These elements are often interconnected via a system or data bus, which is part of a system architecture. Various devices such as graphics adapters may be connected to the system or data bus. Generally, such adapters are directly connected to the bus.
Advanced graphics adapters require an extremely high data transfer rate, but cannot depend on large amounts of data to absorb the start-up cost for each transfer. As a result, an interface to a system bus must be able to start a cycle with minimum latency and transfer data to the graphics adapter utilizing the fastest transfer mechanism available. Additionally, another consideration in designing advanced graphics adapters is the space and power required to allow maximized function and performance. Presently, many advanced graphics adapters are enclosed in a separate box external to a personal computer or work station. Such external graphics adapters require bus master and slave capabilities such as those found on the Micro Channel system bus by International Business Machines Corporation. Micro Channel is a registered trademark of International Business Machines Corporation.
It would therefore be desirable to provide a method and system for providing bus master and slave capabilities via an asynchronous interface between a system bus and an external peripheral device coupled together by a cable.